Method for connecting at least two components of an endoscope, component of an endoscope and endoscope

ABSTRACT

In the case of a method according to the invention for connecting at least two components of an endoscope, at least one brazing preform, which contains a high-temperature brazing solder, is introduced into at least one brazing solder reservoir of at least one of the components, the at least two components are held in relation to one another in such a way that at least one brazing gap that is in capillary connection with the at least one brazing solder reservoir is formed between joining regions of the at least two components that are assigned to one another, and the arrangement comprising the at least two components and the at least one brazing preform is heated to a brazing temperature of the high-temperature brazing solder. The invention also relates to a component of an endoscope and to an endoscope.

This nonprovisional application is a Continuation of U.S. applicationSer. No. 15/088,414 filed on Apr. 1, 2016, which claims priority under35 U.S.C. § 119(a) to German Patent Application No. 10 2015 105 069.2,which was filed in Germany on Apr. 1, 2015, and which is hereinincorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a method for connecting at least twocomponents of an endoscope or medical instrument, to a component of anendoscope that is designed for connecting to at least one furthercomponent of the endoscope by means of high-temperature brazing and forthis purpose has a joining region, and to an endoscope with an endoscopehead, which has a housing and at least one built-in part and/or at leastone built-on part.

Description of the Background Art

Endoscopes are used for many applications in medicine and technology. Anendoscope typically comprises an elongate shank, which is suitable forinserting into a cavity, for instance into a cavity inside the body or acavity in a technical article, and in the distal end region of which,i.e. remote from the user, there is arranged an endoscope objective lensfor producing an endoscopic image of an object field located in thecavity. The shank may be of a rigid, semirigid or flexible design. Therecorded endoscopic image is typically passed on to the proximal end ofthe endoscope, i.e. near the user, by way of an image retransmitterarranged within the shank. Known to act as image retransmitters are inparticular lens systems, which may comprise a plurality of rod lenses,and ordered bundles of optical fibers. Since sufficient light is notgenerally available in the cavity, a light guiding system having opticalfibers is also usually arranged within the shank of the endoscope, inorder to transport light to the distal end of the endoscope forilluminating the object field. Furthermore, the shank may have one ormore working channels for leading through endoscopic workinginstruments, with which manipulations can be carried out within thecavity. Also often provided within the shank are flushing, suction andinsufflation channels, with which liquids or gases can be transportedinto the cavity and out from it during endoscopic operations.

Generally arranged at the proximal end of the shank is an endoscopehead, which remains outside the cavity during the use of the endoscope.The endoscope head has a housing and a plurality of built-in parts andbuilt-on parts. In particular, the endoscope head is adjoined on thedistal side by the shank of the endoscope, on the proximal side by aneyepiece cup or a connection for an endoscopic video camera, and on theside of the endoscope head there is a connection for connecting a fiberoptic cable, with which the illuminating light can be supplied from anexternal light source. Furthermore, the endoscope head may haveflushing, suction and insufflation connections and also inlets ofworking channels, through which endoscopic working instruments can beinserted, as well as guides for the channels and optical elementsarranged within the endoscope head. Typically, at least the housing ofthe endoscope head can be formed of high-grade steel.

During the use and the preparation of an endoscope, it is exposed toconsiderable mechanical, thermal and chemical loads. In particular,vibrations may act on the endoscope, considerable forces may be exertedon the connections during use, and the endoscope is exposed tochemically aggressive media and to increased pressure and increasedtemperature during cleaning and sterilization. It is therefore necessaryto connect the built-in parts and built-on parts to the housing of theendoscope and to one another securely and reliably and in a sealed andthermally stable manner.

For this purpose it is known to connect the components of the endoscopehead to one another by laser welding. However, the melting of thematerial during the laser welding has the effect of weakening thecomponent concerned in the region of the welded connection, which inparticular in the case of thin-walled components, which are used in thecase of endoscopes with a small shank diameter, impairs the strength. Inaddition, laser welding does not always successfully produce afluid-tight connection, in particular in the case of relatively longweld seams. To increase the strength and to ensure the seal-tightness ofa laser-welded connection, it is often additionally secured by adhesion.Since in the production of an endoscope or an endoscope head a pluralityof connections have to be created between components, which moreover areoften arranged within the housing of the endoscope head, and aretherefore only poorly accessible, a large number of successiveproduction steps are necessary, which further increases the productioncosts.

US 2005/0077343 A1 discloses a method for brazing two or more high-gradesteel components of a medical endoscope, wherein one component isconnected to another by means of a brazing solder material that containsat least 62.5% by weight of gold. In this case, the components aresubjected in a first step to a heat treatment at a temperature of 1050to 1200° C. in a hydrogen-containing atmosphere or in a vacuum. In asecond step, one of the components may form a gap with the other, and ina third step the brazing solder material is fed to the gap in a moltenstate in order to connect the components to one another. For feeding inthe brazing solder material, it may be wound as a wire around a tube tobe brazed in, for example, or else be applied as a paste in the regionof the connection. However, this known method is not optimal in terms ofcosts and suitability for use, in particular in the production of anendoscope head.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method forconnecting at least two components of an endoscope, wherein theaforementioned disadvantages are avoided as far as possible. The objectof the present invention is also to provide a component of an endoscopethat is suitable for such a method and also a corresponding endoscope.

A method according to the invention serves for connecting at least twocomponents of an endoscope. In particular, the method serves forpermanently connecting the at least two components with a material bond,i.e. joining them. The components are preferably metallic components, inparticular components of high-grade steel; however, the components mayalso at least partially be formed for instance of titanium, of atitanium alloy or of some other material, preferably metallic material,that is suitable for use in an endoscope and for connection by means ofhigh-temperature brazing.

The endoscope comprises in particular an elongate rigid or semirigidshank, which is suitable for inserting into a cavity and receives anilluminating optical system, for passing on illuminating light from aproximal end region of the endoscope to the distal end region forilluminating an object field to be observed within the cavity, and anobserving optical system, for recording an image of the object field andfor passing on the image to the proximal end region of the endoscope.Connected to the shank in the proximal end region of the endoscope is anendoscope head, which has in particular a light connection forconnecting an optical cable of an external illuminating light source. Onthe endoscope head there may also be provided an eyepiece for the visualviewing of the endoscopic image passed on from the distal end and/or aconnection for an endoscopic video camera. Furthermore, operator controlelements and also the mouths of one or more working, insufflation,suction and/or flushing channels may be arranged at the endoscope head.Such an endoscope is also referred to as an “endoscope optical system”.The endoscope may be an endoscope for medical applications, i.e. forviewing a cavity within a human or animal body, or else a technicalendoscope, which is intended for non-medical applications. The methodaccording to the invention serves in particular for connecting at leasttwo components of the endoscope head, for example a housing of theendoscope head to a built-in part to be inserted into it or to abuilt-on part to be attached to it and/or for connecting a built-in partto another built-in part or a built-on part.

According to the invention, in a first method step at least one brazingpreform, which contains a high-temperature brazing solder, is introducedinto at least one brazing solder reservoir of at least one of thecomponents to be connected to one another. The at least one brazingpreform contains the high-temperature brazing solder for example asmetal powder, which is mixed with a binder and forms a solid or moldablebrazing solder material; the high-temperature brazing solder isconsequently introduced into the at least one brazing solder reservoirin the solid state of aggregation. The at least one brazing solderreservoir may be formed for example as a pocket or cavity of one of theat least two components, into which the at least one brazing preform isintroduced. The brazing preform is preferably preformed in such a waythat it can be easily introduced into the brazing solder reservoir, forinstance can be pushed in, and substantially fills the reservoir.

In a second method step, the at least two components to be connected toone another are arranged and held in relation to one another in such away that at least one brazing gap is formed between joining regions ofthe at least two components that are assigned to one another. Thejoining regions are regions corresponding to one another of the surfacesof the components that are arranged such that they are in particularopposite one another at a small distance and thereby form a brazing gap.The joining regions respectively assigned to one another of the at leasttwo components form a joining location. The brazing gap is in capillaryconnection with the at least one brazing solder reservoir, i.e. theconstruction of the brazing solder reservoir and the arrangement of thecomponents in relation to one another is such that, after melting, theliquid solder can be drawn out of the brazing solder reservoir into thebrazing gap by capillary forces, in order to completely or partiallyfill this gap. For example, the at least one brazing solder reservoirmay have an opening that opens out into the brazing gap or is inconnection with it directly or is in connection with the brazing gap byway of a capillary or a gap that corresponds in its width substantiallyto the brazing gap. The opening of the brazing solder reservoir may bethe same as that through which the brazing preform has been introducedinto the brazing solder reservoir. In the second step of the methodaccording to the invention, the high-temperature brazing solder iscontained in the at least one brazing preform while still in a solidform.

The second method step may be performed at the same time as thefirst-mentioned first method step or, depending on the type andconstruction of the components to be connected to one another anddepending on the accessibility of the at least one brazing solderreservoir, may also take place before the aforementioned first step.Thus, it may be provided for example that the at least one brazingsolder reservoir is only created by the arrangement of the at least twocomponents, and the at least one brazing preform is only introduced intothe at least one brazing solder reservoir after the components have beenarranged in relation to one another.

Furthermore, according to the invention, in a third method step, thearrangement, created by the first method step and the second methodstep, possibly by carrying out the first method step and the secondmethod step for a number of joining locations and comprising the atleast two components to be connected to one another, including the atleast one brazing preform introduced in the at least one brazing solderreservoir, is heated to a brazing temperature of the high-temperaturebrazing solder, i.e. in particular to a temperature that corresponds atleast to the melting temperature of the high-temperature brazing solder.The heating may be carried out for instance in a furnace, which may forexample be a continuous furnace; in this case, the heating may takeplace in a known way under shielding gas or in a vacuum, wherebytarnishing of the surface and slag formation can be avoided. Heating tothe brazing temperature has the effect that the high-temperature brazingsolder is liquefied, after which it is drawn out of the brazing solderreservoir into the at least one brazing gap by capillary forces andcompletely or partially fills the gap. Once the solder has filled the atleast one brazing gap, the arrangement is left to cool down until thehigh-temperature brazing solder has solidified and the at least twocomponents have been connected to one another by the brazed connection.

The method according to the invention may comprise further steps, forinstance a pretreatment of the components to be connected to one anotheror the joining regions, in order to facilitate the flowing of theliquefied solder into the at least one brazing gap. Further methodsteps, which may in particular concern the production of the components,the at least one brazing preform and the assembly and adjustment of theendoscope, may also be provided before, between or after theaforementioned three method steps in the course of the production of theendoscope.

The fact that the high-temperature brazing solder is provided as atleast one brazing preform which is introduced into at least one brazingsolder reservoir of at least one of the components to be connected toone another means that it is made possible for brazed connections thatare seal-tight and can withstand high loads can be easily created, evenin the case of complex geometries of the components connected to oneanother. At the same time, greater stability of the joining locationsand also an increase in quality with regard to the seal-tightness can beachieved in particular by a connecting area that is larger in comparisonwith laser welding, and also by no material of the components to beconnected being melted. Furthermore, simplification of the productionprocess is made possible, generally obviating the need for additionalfixing or sealing of the joining locations by means of adhesive. It isoften possible when connecting the at least two components of theendoscope or when producing an endoscope head by the method according tothe invention to dispense largely or entirely with laser welding,whereby the runthrough time in production can be reduced and theproduction costs can be lowered. Furthermore, manual feeding of thebrazing solder is not necessary, as a result of which the productionprocess can likewise be simplified, and what is more an always constantamount of brazing solder can be ensured. Similarly, the components to beconnected to one another can themselves be of a structurally simplerdesign, since no special measures are necessary for making laser weldingpossible on internal components; what is more, a weight saving may beachievable as a result.

According to a preferred embodiment of the invention, for forming the atleast one brazing gap, the at least two components are held in relationto one another, at least on the basis of the previously described secondmethod step, by the components being held against one another withinterlocking, frictional or material-bonding engagement. The twocomponents to be connected to one another may for example be fastened toone another by a thread or by individual laser welding points andthereby held in such a way that the at least one brazing gap is createdand sustained during the further method steps, in particular the thirdmethod step. This may make it possible to dispense with an auxiliarydevice for joining the at least two components. As a result, theproduction of the endoscope can be further simplified.

In an advantageous way, the at least two components to be connected toone another may have a plurality of joining locations, to which at leastone brazing solder reservoir is respectively assigned. Preferably, eachjoining location is assigned precisely one brazing solder reservoir. Thejoining locations may be respectively formed by, a joining region of afirst component and a joining region assigned thereto of a secondcomponent that is to be connected to the first, the number of joininglocations preferably not being contiguous with one another but formedseparately. The fact that the at least two components to be connected toone another have a plurality of joining locations to which at least onebrazing solder reservoir is respectively assigned means that aparticularly reliable and secure connection of the at least twocomponents is made possible. This applies in particular in the casewhere the components to be connected to one another have a complexgeometry or the joining locations are poorly accessible. Furthermore, itis possible in particular according to the invention to connect aplurality of joining locations with the high-temperature brazing solderin a single heating step, whereby the production of an endoscope or anendoscope head can be further simplified.

More than two components are preferably connected to one another, atleast two joining locations being provided. Here it is likewise possibleto make use of the fact that a number of joining locations, inparticular all of the joining locations, can be filled withhigh-temperature brazing solder simultaneously or in a single heatingstep. This allows the number of necessary production steps in theproduction of an endoscope or an endoscope head to be further reduced,and consequently production to be further simplified.

In the event that a number of joining locations are provided or morethan two components are connected to one another, it may be provided inparticular that the first method step and the second method step arecarried out for a first joining location or for the connection of afirst component to a second component, after that the first method stepand the second method step are carried out for a second joining locationor for the connection of the first component and/or the second componentto a third component, and after that are possibly carried out forfurther joining locations or components. The sequence of the firstmethod step and the second method step may be different for each joininglocation or each further component. The sequence of the method steps mayin this case be chosen according to the type and construction of thecomponents to be connected to one another and according to theaccessibility of the brazing solder reservoirs concerned.

According to a particularly preferred embodiment of the invention, thehigh-temperature brazing solder is a nickel-based solder or iron-basedsolder. Such a nickel-based solder or else nickel solder contains anickel fraction of for example approximately 75% and may contain furthermetallic and/or nonmetallic constituents. The brazing preform mayadditionally contain a binder, which evaporates during the heating step.When using a nickel-based solder, the brazing temperature lies forexample in the range between 1050 and 1200° C. In particular whenheating in a vacuum or under a shielding gas, a flux is generally notrequired, whereby flux inclusions can also be avoided and the corrosiontendency can be reduced. Use of a nickel-based solder allows aparticularly secure connection of the at least two components to beachieved. Furthermore, as a result, discoloration of visible brazedseams during the sterilization necessary for medical endoscopes, inparticular autoclaving, can be easily avoided. Nickel-based solder isparticularly advantageous for connecting components of high-grade steel;for components of other materials, a different brazing solder materialmay be used, for instance titanium solder for connecting components oftitanium.

The brazing preform is preferably produced from a brazing mat, forexample by punching out from a sheet-like brazing mat. In this case, thebrazing mat may have previously been rolled out to a suitable thickness.The brazing mat may contain the high-temperature brazing solder inpowder form, and also a binder and possibly further constituents. As aresult, the preparation of a brazing preform of the desired dimensionsfor filling the at least one brazing solder reservoir is made easilypossible.

According to a preferred embodiment of the method according to theinvention, after being introduced into the brazing solder reservoirconcerned and before heating, the at least one brazing preform is fixedwithin the brazing solder reservoir. Such fixing may take place forexample with interlocking or frictional engagement, for which thebrazing solder reservoir is correspondingly shaped, for instance as apocket, which is filled virtually completely by the brazing preform. Theat least one brazing preform is preferably fixed in the respectivebrazing solder reservoir by adhesion. An adhesive used for this purposemay in particular comprise a solvent, which makes an uppermost layer ofthe brazing mat or the brazing preform begin to dissolve. As a result,the brazing preform is adhesively attached on the surface of thecomponent concerned, i.e. on the inner surface of the brazing solderreservoir. It is thereby easily possible to achieve the effect that thebrazing preform remains in place during further handling, up until themelting of the high-temperature brazing solder, and that the liquefiedhigh-temperature brazing solder flows into the brazing gap assigned tothe brazing solder reservoir. As a result, the handling of thecomponents to be connected to one another is simplified, so that even aplurality of components can be easily connected to one another with aplurality of joining locations.

The brazing solder reservoir and the brazing preform are preferably atleast dimensioned in such a way that the at least one brazing solderreservoir is substantially filled by the brazing preform introduced intoit and during the heating the brazing gap assigned to the at least onebrazing solder reservoir is substantially filled completely with thehigh-temperature brazing solder. In particular, the volume of thebrazing solder reservoir may be at least equal to the volume to befilled of the brazing gap; the volume of the brazing solder reservoir ispreferably made to be greater than the volume of the brazing gap by atleast an amount that corresponds to the proportion of the binder in thebrazing preform. In addition, an excess of brazing solder materialbeyond that and a correspondingly greater dimensioning of the brazingsolder reservoir and the brazing preform may be provided. The excess mayserve for example for ensuring complete filling of the brazing gap evenwhen tolerances occur, and may possibly remain in the brazing solderreservoir after the melting. In particular, depending on the geometry ofthe joining location, an excess may be provided in order in addition tothe filling of the brazing gap to form a fillet seam. The fact that thebrazing solder reservoir and the brazing preform are dimensioned atleast such that the brazing solder reservoir is filled by the brazingpreform and furthermore the brazing gap is filled substantiallycompletely with the high-temperature brazing solder means that aparticularly reliable and seal-tight connection of the at least twocomponents to be connected to one another can be achieved.

A component according to the invention of an endoscope, in particularthe head of an endoscope, is designed for connecting to at least onefurther component of the endoscope or the endoscope head by means ofhigh-temperature brazing, in particular for connecting to the at leastone further component by means of the method according to the inventionthat is described above. For this purpose, the component according tothe invention has a joining region, which is designed to form togetherwith a corresponding joining region of the further component a joininglocation for the connection of the two components. According to theinvention, the component has a brazing solder reservoir assigned to thejoining region or the joining location. The brazing solder reservoir isdesigned to receive a brazing preform, which contains a high-temperaturebrazing solder and is arranged in such a way that the high-temperaturebrazing solder liquefied by heating can flow under the effect of brazingforces into a brazing gap that can be formed between the joining regionof the component and a joining region of the further component and canat least partially fill this gap. The brazing solder reservoir isarranged in such a way that it is in capillary connection with a brazinggap that can be formed between the joining regions assigned to oneanother of the component and the at least one further component, forinstance in that the brazing solder reservoir has an opening that opensout into the joining region of the component or is in connection with itby way of a capillary. The way in which the component of the endoscopeis configured according to the invention makes it possible for aconnection that is secure and seal-tight even in the case of relativelylong brazed seams to be easily produced between the component accordingto the invention and the further component.

An endoscope according to the invention comprises an endoscope head andan elongate, preferably rigid or semirigid shank, in which anilluminating optical system and an observing optical system are receivedand which is connected to the endoscope head. The endoscope head has ahousing and at least one built-in part and/or at least one built-onpart, the at least one built-in part, the at least one built-on partand/or the housing being designed in the same way as the componentdescribed above. In particular, the housing and/or the at least onebuilt-in part and/or the at least one built-on part have been connectedto one another by means of high-temperature brazing solder and connectedto one another by the method described above. The at least one built-inpart may for example be an inner bush for receiving a proximal endportion of an optical tube for receiving the observing optical systemand possibly a lightguide channel for receiving the light guides of theilluminating optical system. Further built-in parts may serve forexample for holding optical components within the endoscope head and/orfor guiding working, insufflation, suction and/or flushing channels. Theat least one built-on part may for example be a sleeve of a lightconnection for connecting an optical cable of an external illuminatinglight source. Further built-on parts of the endoscope head may be forexample the mouth of a working channel and insufflation, suction and/orflushing connections, as well as an outer shank of the endoscope. Thefact that the at least one built-in part, the at least one built-on partand/or the housing are designed as described above, and consequently aredesigned for connecting by means of the method according to theinvention that is described above, and in particular have been connectedto one another by the method according to the invention, means that anendoscope is created with an endoscope head in which the at least onebuilt-in part or the at least one built-on part are connected to thehousing or to one another in a secure and hermetically seal-tightmanner, and which can be produced in an easy and low-cost way.

It goes without saying that the features that are mentioned above andthose still to be explained below can be used not only in therespectively specified combination but also in other combinations or ontheir own without departing from the scope of the present invention.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes. combinationsand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus, are not limitiveof the present invention, and wherein:

FIGS. 1a to 1 c show a housing of the endoscope head of an exemplaryembodiment of an endoscope according to the invention in an end view, asectional view and an oblique view;

FIGS. 2a to 2c show a built-in part for the housing of FIGS. 1a to 1c incorresponding views, FIG. 2 showing an enlarged sectional view;

FIG. 3 shows a brazing preform for use with the built-in part accordingto FIGS. 2a to 2c in a plan view;

FIGS. 4a and 4b show a built-on part for the housing of FIGS. 1a to 1cin two views;

FIGS. 5a to 5c show an arrangement of the components of FIGS. 1a to 4bfor the brazing process in an end view, a sectional view and an obliqueview;

FIG. 6 shows an arrangement for the high-temperature brazing ofcomponents for the head of an endoscope according to a further exemplaryembodiment of the invention in a longitudinal section.

DETAILED DESCRIPTION

Represented in a simplified form in FIGS. 1a to 5c are components of anendoscope head that are designed for connecting according to anexemplary embodiment of the method according to the invention, and alsothe arrangement 1 of the components set up for the brazing process. FIG.1a shows the housing 2 of the endoscope head in an end-on view.Represented in FIG. 1b is a longitudinal section of the housing 2 alongthe line B-B (see FIG. 1a ). FIG. 1c shows the housing 2 in an obliqueview. The housing 2 is of a substantially cuboidal design, or isdesigned in the form of a square column with beveled edges. The housing2 has a substantially cylindrical bore 3, which passes right through inthe longitudinal direction and the openings at both ends of which areformed in a stepped manner, an annular, likewise stepped stop 4 beingprovided in one of the openings. The side walls of the housing 2 areprovided with transverse bores 5, 6.

In FIGS. 2a to 2c , a built-in part that is designed as an inner bush 7and is designed for inserting into the housing 2 shown in FIGS. 1a to 1cand for connecting to the latter by high-temperature brazing isrepresented in an end-on view, as a longitudinal section along the lineB-B (see FIG. 2a ) and in an oblique view. The inner bush 7 has a shank8, which is cylindrical in certain portions and bears at each of its twoends a disk 9, 10 and in its middle part an enlarged cylinder 11. Theinner bush 7 has a longitudinal through-bore 12. The cylinder 11 has twotransverse bores 13, 14, which reach into the longitudinal bore 12. Thedisks 9, 10 and the cylinder 11 respectively have an incision, which isformed as a peripheral annular groove 15, 16, 17 and serves as a brazingsolder reservoir. As shown in the enlarged representation of FIG. 2b ,in comparison with FIGS. 2a and 2c , the annular grooves 15, 16, 17respectively have a rectangular cross section. Correspondingly preformedbrazing preforms may be introduced into the annular grooves 15, 16, 17.

A brazing preform suitable for introducing into the annular grooves 15,16, 17, designed as a brazing ring 18, is schematically represented inFIG. 3. The brazing ring 18 is produced by punching out from a brazingmat with a respectively suitable thickness, the thickness of the brazingmat corresponding approximately to the width of the respective annulargroove 15, 16, 17, into which the brazing ring 18 is introduced. Thewidth of the brazing ring 18 corresponds substantially to the depth ofthe respective annular groove 15, 16, 17. The brazing mat, andconsequently the brazing ring 18, contains a high-temperature brazingsolder in solid form, for instance as powder. In particular, the brazingmat may be produced powder-metallurgically with a nickel-based solder oriron-based solder and a binder. The brazing ring 18 may be deformable orelse for instance be divided into ring segments, in order to facilitatethe introduction into the annular grooves 15, 16, 17. The brazing ring18 or the ring segments may be fixed in the annular grooves 15, 16, 17with frictional or interlocking engagement or preferably by an adhesiveintroduced beforehand into the respective annular groove 15, 16, 17.

Also represented in two views in FIGS. 4a and 4b is a connecting part19, which can be attached to the housing 2 of the endoscope head. Theconnecting part 19 may serve for example as a flushing connection or asa light connection and has for this purpose a through-bore 20.

In FIGS. 5a to 5c , the arrangement 1 comprising the housing 2, theinner bush 7 and the connecting part 19 and also a further connectingpart 21, including the inserted brazing preforms which have been puttogether for the brazing operation, are shown in an end-on view (FIG. 5a). FIG. 5b shows the arrangement 1 in a longitudinal section along theline B-B (see FIG. 5a ), and FIG. 5c shows the arrangement 1 in anoblique view. As can be seen in particular in FIG. 5b in comparison withFIGS. 1b and 2b , the inner bush 7 has been inserted into the bore 3 ofthe housing 2 in such a way that the disk 9 of the inner bush 7 liesagainst the step of the stop 4. The two disks 9, 10 fill the respectiveopenings of the bore 3 apart from peripheral brazing gaps formed betweenthe outer circumference of the disk 9, 10 and the inner wall of thehousing 2; similarly, a brazing gap is formed between the outercircumference of the cylinder 11 and the inner wall of the housing 2.The connecting parts 19, 21 have been inserted into the transverse bores5, 6 of the housing 2 in such a way that the transverse bores 13, 14 ofthe inner bush 7 continue into corresponding inner bores 20 of theconnecting parts 19, 21. As can be seen in particular in FIG. 5b , thebrazing solder reservoirs formed by the annular grooves 15, 16, 17 areadjacent the brazing gaps between the inner bush 7 and the housing 2.Furthermore, the brazing solder reservoir formed by the annular groove16 provided in the cylinder 11 is adjacent the joining locations betweenthe connecting parts 19, 21, the cylinder 11 and the housing 2, wherecorresponding brazing gaps are likewise provided. In order to formbrazing gaps suitable for high-temperature brazing, the housing 2 and/orthe inner bush 7 may have projections, with which the inner bush 7 isheld with frictional contact within the housing 2, or the inner bush 7may be held in an appropriate position within the housing 2 byindividual laser welding points (not represented in the figures); thesame applies correspondingly to the connecting parts 19, 21.

In FIG. 5b , it is indicated that a respectively fitting brazing ring 18has been inserted into the annular grooves 15, 16, 17. This ring isdimensioned to respectively fill the volume of the annular groove 15,16, 17 and provide the amount of liquid brazing solder required forfilling the respectively assigned brazing gap. For this purpose, thevolume of the respective annular groove and the brazing ring 18 insertedtherein may for example be greater by approximately 10% than that of theassigned brazing gap, in order to compensate for the loss of volume dueto evaporation of the binder.

For connecting the housing 2, the inner bush 7 and the connecting parts19, 21, a respectively fitting brazing ring 18 is inserted into theannular grooves 15, 16, 17. Then, the inner bush 7 fitted with thebrazing rings 18 is inserted into the housing 2 and possibly heldtherein by further measures, for instance laser welding points.Furthermore, the connecting parts 19, 21 are inserted into thetransverse bores 5, 6 of the housing 2 and possibly held therein byfurther measures. The components mentioned may form a subassembly. Thearrangement 1 shown in FIGS. 5a to 5c , comprising the housing 2, theinner bush 7 with the brazing rings 18 and the connecting parts 19, 21,is then heated in a continuous furnace to a temperature that lies abovethe melting temperature of the high-temperature brazing solder containedin the brazing rings 18. The high-temperature brazing solder ispreferably a nickel-based solder or an iron-based solder, and thebrazing temperature to which the arrangement 1 is heated lies in therange between 1050 and 1200° C., the temperature being kept in thisrange for for example 10 to 15 minutes. The high-temperature brazingsolder thereby liquefies and, on account of the capillary action, flowsinto the brazing gaps formed between the components to be connected toone another. During the subsequent cooling down, which may take placefor example within one hour or within a few hours, the high-temperaturebrazing solder solidifies in the brazing gaps and thereby creates asolid, durable and seal-tight connection between the components to beconnected to one another. The assembly produced is provided with furthercomponents in further steps of producing the endoscope.

In FIG. 6, an arrangement 22 comprising components for an endoscope headaccording to a further exemplary embodiment of the invention isrepresented in a partly sectioned sectional view. The endoscope head hasan approximately cuboidal housing 23 with a longitudinal bore that iscylindrical in certain portions and into which an inner bush 24 andfurther built-in parts 25, 26 can be inserted. Attached obliquely ontothe housing 23 is a light connection with a light connecting sleeve 27.An intermediate piece 28 is arranged between the light connection andthe inner bush 24. Also provided are openings 29, 30, into which furtherbuilt-on parts, for example flushing and suction connections, can beinserted. The inner bush 24 is designed for receiving an optical tubeand a lightguide channel of the endoscope and the intermediate piece 28is designed for guiding optical fibers.

Furthermore, in FIG. 6 a number of joining locations are represented byway of example, with the associated brazing solder reservoirs or thebrazing preforms inserted therein. For providing the high-temperaturebrazing solder for a brazing gap, which is formed between the built-inpart 25 and the inner side of the housing 23, a first brazing ring 31 isinserted in a brazing solder reservoir formed by an annular collar 32and fixed there by adhesion. For bounding the brazing solder reservoir,the annular collar 32 has a wall extending transversely in relation tothe longitudinal direction, as a termination on one side in thelongitudinal direction, and a wall perpendicular thereto as a connectionon the inner side. The brazing ring 31 may be inserted into the brazingsolder reservoir in the longitudinal direction. For connecting thefurther built-in part 26 to the housing 23, a second brazing ring 33 isattached to the inner side of the housing 23 and the built-in part 26 ina region in which the built-in part 26 butts against a step 34 of thehousing 23, and is fastened there by adhesive; the brazing solderreservoir is likewise bounded here by an annular collar 35. Forproviding the brazing solder for filling a brazing gap between the lightconnecting sleeve 27 and an outer side of the housing 23, a brazingsolder reservoir filled with an elliptical brazing ring 36 is providedbetween the housing 23 and the light connecting sleeve 27. Theintermediate piece 28 is connected to the housing 23 by way of a joininglocation that is formed between the outer wall of the intermediate piece28 and a transverse sleeve 37 of the housing 23, for which a brazingring 38 is likewise provided in a corresponding brazing solderreservoir.

The brazing gaps of the joining locations typically have a width of oneor several tenths of a millimeter, a height of approximately one orseveral millimeters and a length in the range of millimeters orcentimeters, so that a required volume of the high-temperature brazingsolder of several mm³ is obtained. The brazing solder reservoirs and thebrazing rings 31, 33, 36, 38 inserted into them are dimensionedcorrespondingly to provide the appropriate amount of high-temperaturebrazing solder. In particular, the volume of the brazing solderreservoir and of the respective brazing ring 31, 33, 36, 38 isapproximately 10% greater than the required volume of thehigh-temperature brazing solder, in order to compensate for theevaporation of the binder. Furthermore, the brazing ring 36 inparticular may additionally be made to greater dimensions, in order tomake an additional brazing solder volume available for the formation ofa fillet seam.

The arrangement 22 shown in FIG. 6 may be heated as a whole in afurnace, for instance a continuous furnace, to a brazing temperature.The in the brazing rings 31, 33, 36, 38 and possibly further brazingpreforms not represented in FIG. 6, which are assigned to furtherjoining locations, liquefies and flows into the brazing gaps of thecorresponding joining locations. As a result, a plurality of componentscan be connected to one another with a plurality of joining locations ina single operation, irrespective of the accessibility of the joininglocation. As a result, a considerable simplification of the productionprocess can be achieved. In further production steps, furthercomponents, for instance an optical tube, an eyepiece cup, light guidesand also the shank of the endoscope, are inserted into the assemblycreated or are attached to it (not represented).

For the sake of overall clarity, not all of the designations arerepresented in all of the figures. Designations that are not explainedin relation to one figure have the same meaning as in the other figures.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are to beincluded within the scope of the following claims.

What is claimed is:
 1. An endoscope comprising: at least two componentsconnected together by a brazing solder provided in at least one brazinggap between joining regions of the at least two components, wherein oneof the at least two components has at least one brazing solder reservoirthat is in capillary connection with the at least one brazing gap, andwherein the at least one brazing solder reservoir and the at least onebrazing gap being formed such that a volume of the at least one brazingsolder reservoir is greater than a volume of the at least one brazinggap by at least an amount that corresponds to a proportion of a binderin the brazing solder.
 2. The endoscope according to claim 1, whereinthe at least two components each have at least two joining regions. 3.The endoscope according to claim 1, wherein the brazing solder is anickel-based solder or an iron-based solder.
 4. The endoscope accordingto claim 1, wherein one of the at least two components is an endoscopehead having a cylindrical bore, and wherein another one of the at leasttwo components is an inner bush that is received within the cylindricalbore of the endoscope head.
 5. The endoscope according to claim 4,wherein the inner bush is formed of a shank having a bore extendingtherethrough, wherein, at each end of the shank, a disk extends aroundan outer periphery of the shank, and wherein, at a central area of theshank, a cylinder extends around an outer periphery of the shank.
 6. Theendoscope according to claim 5, wherein the at least one brazing solderreservoir is provided as an annular groove in at least one of the disks.7. The endoscope according to claim 5, wherein the cylinder has a boreextending therethrough in a direction transverse to the bore of theshank.
 8. The endoscope according to claim 7, wherein the bore of thecylinder opens into the bore of the shank.